The requirements and performance of compositions used for sealing rock and soil have increased over time. The requirements involve both improved environmental and technical aspects. Previously, various plastics and polymers involving toxic substances have been employed to seal water leaks in e.g. concrete walls, tunnels, dumps etc. Such sealing chemicals have in a number of cases caused contamination of groundwater and health problems. However, attempts have been made to replace hazardous products with more environmentally adapted ones. New products have also been sought for to meet the recently imposed leakage restrictions. Water leakage levels as low as 1 liter/(min*100 meters) have occasionally been the upper threshold on constructions sites of tunnels. U.S. Pat. No. 5,396,749 describes a method for cutting off a water flow by grouting whereby water leakage and collapse of ground is prevented. The cut-off agent is prepared by mixing e.g. colloidal silica, inorganic salt, and a water-soluble urethane polymer. However, the strength of these agents has shown to be insufficient in several applications, particularly where the agent during injection and gelling is exposed to a high water pressure. Especially unstable agents have during the ageing phase resulted in a fairly low long term strength.
Sealing agents have also been used for sealing soil to prevent leakage of contaminants in subterranean areas like buried sources, dumps etc. U.S. Pat. No. 5,836,390 discloses a method of forming subsurface barriers where a viscous liquid comprising polybutenes, polysiloxanes, and colloidal silica is injected. However, such barriers are not always sufficiently strong to prevent aqueous and organic liquids from penetrating. Further to this, stability problems or pre-gelling of the sealing composition have many times rendered the sealing procedure inefficient.
It would be desirable to provide a stable and environmentally adapted liquid cut-off agent having a high early strength as well as long term strength, especially in the field of sealing rock, where the cut-off agents may be subjected to high water pressure from groundwater. It would also be also desirable to provide durable products which resist washout forces and have a low permeability or even impermeable to water and other liquids.
It is therefore an object of the present invention to provide products solving the drawbacks of the prior art.